During my recent testimony before the Senate Budget Committee (found here), I cited an OECD statistic that the U.S. has the most progressive income tax system among industrialized nations.

The first column shows that the top 10 percent of households in the U.S. pays 45.1 percent of all income taxes (both personal income and payroll taxes combined) in the country. Italy is the only other country in which the top 10 percent of households pays more than 40 percent of the income tax burden (42.2%). Meanwhile, the average tax burden for the top decile of households in OECD countries is 31.6 percent.